Here are my guesses: My centerboard tends to rattle a bit when I'm running. The sound is not exactly as you describe however. Another possibility is that the mast is twisting a bit in the tabernacle and since it is mounted on the cabin top, the sound resonates and seems to come from the cabin. I've heard this sound when running as well and while sea lion barks didn't come to mind, it does make a kind of groaning sound. Hank M-15 -----Original Message----- From: montgomery_boats-bounces+kwanthb=msn.com@mailman.xmission.com [mailto:montgomery_boats-bounces+kwanthb=msn.com@mailman.xmission.com] On Behalf Of Bobbie Mayer Sent: Monday, August 14, 2006 5:25 PM To: montgomery_boats@mailman.xmission.com Subject: M_Boats: Groaning M15 Yesterday we sailed my M15 about six miles downwind and downcurrent, most of the way wing and wing, and at one point heard kind of a groaning sound which sounded like it was coming from the cabin. (Sort of like sea lions make.) Any idea what could be making it? Bobbie -- _______________________________________________ http://mailman.xmission.com/cgi-bin/mailman/listinfo/montgomery_boats